Concerning pyridonecarboxylic acid type synthetic antimicrobial agents, it is known that the substituent at the 7-position of the quinoline skeleton thereof (or 10-position of the pyridobenzoxazine skeleton) has influences on antimicrobial activity. Various groups have been proposed as a substituent at the 7-position. In particular, pyridonecarboxylic acid derivatives having a 3-aminopyrrolidinyl group at the 7-position are known to exhibit potent antimicrobial activity and a broad antimicrobial spectrum against both Gram-negative and Gram-positive bacteria.
Pyridonecarboxylic acid derivatives comprised of a 3-aminopyrrolidinyl group and a pyridobenzoxazine skeleton are believed to have low lipophilic properties, and their pharmacokinetic properties are not good probably due to poor absorption from intestinal tracts.